Sperm maturation probably requires interaction of sperm with specific secretory products of the epididymal epithelium. Sperm maturation occurs in the proximal epididymis if locally produced dihydrotestosterone is available to stimulate secretion by the epithelial cells. Maintenance of the enzyme 5Alpha-reductase may be dependent on continuous availability of component(s), possibly androgen binding protein, in rete testis fluid. In preparation for testing the hypotheses that a factor(s) in rete testis fluid controls activity of epididymal 5Alpha-reductase and hence epididymal secretion and that secretion of principal cells from specific regions of the epididymis bind to immature sperm and alter their function, we have developed a procedure to culture principal cells from specific regions of the ram epididymis. Ovine rete testis fluid and immature sperm will be obtained by cannulating the rete testis. Two potential control points for contraceptive action will be examined by studies aimed at (a) identification of the regulatory component(s) in rete testis fluid and (b) establishment of the role of eipididymal secretory products in sperm maturation. The role of rete testis fluid in controlling epididymal function will be studied by culturing highly purified preparations of ram principal cells, from specific regions, of the epididymis, in media containing 20 or 100% concentration of ram rete testis fluid or fractions thereof. Cell response will be measured by activity of 5Alpha-reductase, cell ultrastructure, and qualitative analyses of secreted proteins. The role of the hormonal milieu (androgen, progesterone, estradiol and aldosterone) on characteristics of the cells and their secretions will be evaluated similarly. Differences among secretions from different regions of the epididymis will be examined. Finally, the binding of secreted proteins by immature (testicular) ram sperm will be examined and the responses of the sperm to bound secretory protein will be evaluated. Success in manipulation of either control point for opididymal function could allow inhibition of sperm maturation oand reversible contraception.